This invention relates to concrete screeds and in particular to a portable screed which is guided by one or more operators to smooth freshly-poured concrete prior to finishing and curing.
As set forth in my U.S. Pat. No. 4,591,291, smoothing and leveling of freshly-poured concrete is done in essentially two ways. In a more automated manner, concrete screeds such as that described in my U.S. Pat. No. 4,340,351 are used. More traditionally, the concrete is manually leveled by two or more laborers by moving a board across the surface of the fresh concrete.
While either process results in relatively level concrete, modern-day tolerances require perfectly-leveled concrete within precise tolerances. Thus, sight levels, surveyors' levels, and other devices have been employed with some degree of accuracy. As allowable tolerances decreased, however, greater precision is demanded, and such means often are inadequate to assure proper concrete leveling.